Tuesday, July 31, 2012

The coamings required some of the trickiest fits yet, short of the frames. The frames were harder, but there was less at stake because they were painted into the boat, whereas the coamings are finished bright. Any misses will be obvious under varnish. Preparation for the decks and coamings began early, and I covered some of this in previous posts. Deck layout was covered in Part 7, and the curved beams and coaming lamination were covered in Part 12. The curved coaming pieces have been hanging up in the shop, waiting for me to get back to them.

A brief description of the concept is in order, though. The curved parts at each end are laminated from 7 layers of 1/16" vertical grain sapele veneer. The two straight parts are re-sawn from a 5/4 v.g. sapele board, to make two sides, and finished to 7/16" to match the curved bits. The joins from curved to straight are half lapped, with a joint length of 2". I did not make patterns for any of it, but marked and cut the pieces straight from the boat. The curved pieces were hung with with clamps, and temp. screwed so that they would return to their exact location after cutting. I was only concerned with the end cuts of each piece at first. I waited until all pieces were fit and joined before cutting any of it to final width, leaving plenty of room for all the pieces to move up or down to tune the joints.

The curved ends are clamped up and marked for cutting.

I first decided where I wanted the joins to be, and marked this location on the ends of the curved pieces. I know its fast to make this kind of cut by hand, but I've got a great sliding table saw with all kinds of hold downs only six feet away, so that's how I made the end cuts.

I have a great table saw, might as well use it!

I used a router with a top bearing cutter and scrap mdf for a guide, clamped to the coaming. I hardly ever use this one, but the ancient old vintage Stanley router had the right cutter in the collet already, so I dug it out. This thing is at least 50 or 60 years old, and is fun to look at, plus it works fine. The big wing nut that tightens the motor in the base has never worn out. The D handle Porter Cables all have replacement bolts with nuts because the aluminum wing nuts they come with wear out so quickly. I set the depth a little shy of half way, and tuned the cut with a rabbet plane afterwards. Half way through the center veneer is a handy visual reference for the correct depth of the first half of the joint. These cuts were made fairly quickly, and the coamings hung with temp. screws.

The vintage Stanley.

The half lap is evident here on the curved end, where it joins to the straight part.

If you look close, you can see the cut is half way through the middle veneer layer.

I next clamped one of the straight parts in the boat, and roughly marked out the sheer curve and length (left a couple of inches long). At this point, I just wanted plenty of width to work with, so they appear quite high in the pictures.

The straight pieces are clamped in, to determine their length.

This shows the amount of sheer curve there is to cut.

I figured out the correct angle of the end cut on these straight pieces, and made the half lap in one end, checking the fit of the joint on the boat. The first one's easy. The trick is getting the exact length of the piece figured out, to make the joint at the other end. The piece won't fit until every little bit of curve is clamped into the coaming, and there it gets too short real fast. What I did was transfer a reference mark from the deck to the outside of the coaming piece. I then took a thin scrap of ply and butted it to the join at the other end (with the correct angle cut on the end of this stick), bent it tightly around the carlin, and marked the reference on the ply. I lined up the reference mark from the ply piece to the actual coaming, and marked the end cut (at the proper angle), but I also added 1/8" to the length, hedging my bets. I cut that half lap, and hung the coaming back in the boat. It came out longer than the extra 1/8", but it was fairly easy to mark the correct length the second time, and re-cut the joint. The piece won't fit, as I said before, until every bit of the curve is in the piece. I used a mallet and a block to drive the first end tightly in place, and finally was able to snap the section in. I ended up fussing and tuning these joints quite a bit before I was finally satisfied, though on the next one I was more cavalier in my approach. I will admit to needing a tiny shim on the outboard port side aft, but its matched well, and is not noticeable at all.

The half lap fits well. The top and bottom cuts will bring everything to a fair line.

With the joints all fitted, I marked out the top and bottom cuts around the entire perimeter of the coaming. I made up a gauge block to find the bottom edge, since this was a constant height below the deck. This block has a slot to fit over the coaming, a leg that rides on the deck, and a longer leg that hangs done inside the boat. By running this block all around the boat, the lower edge is marked. I also put a screw reference mark on the jig, to keep the screw heights consistent (the fore and aft spacing of the screws was already marked out).

A simple height gauge block to mark the bottom edge of the coaming.

The gauge in use. Note the tick mark for screw heights.

The top cut was marked with a simpler gauge block that just rode around the deck. I cut the coaming 3/4" above the deck, no higher than the oarlock pads so as not to interfere with the oars. In the curved ends, I sprung in a little more height to give the deck more shape. The transition is tricky, and I did the best I could. Its not perfect, but it looks pretty good.

I then had to pull everything back out of the boat, and cut the top and bottom lines on the four pieces of coaming. I also rounded over all the edges, except right at the half laps, where there would be some final fairing to do after glueing it all in place. One trick I've learned when bonding bright finished pieces with epoxy, is to pre-sand and seal everything with a coat of shellac. This keeps epoxy off of the wood, and out of the grain, making for a much cleaner installation. I tape off the areas to be bonded of course, before shellacking. I mix my own shellac fresh, using amber flakes and Bekhol, and use about a 2 lb. cut for sealing.

The finished coaming parts get a coat of shellac.

After shellacking, I pulled off the tape, and reapplied it to mask off the areas around around the glue joint. I also masked off the deck, to keep that as clean as possible, and papered the boat interior as well. I'm a stickler for keeping epoxy off the boat. It pays off in spades down the road. Two of us glued up all the pieces of the coaming in one go. Help was nearly mandatory for this job, springing in and driving all the gluey parts home, then cleaning up the squeeze out. It took us 2-1/2 hours, start to finish. After curing, I faired all the transitions, and that's where we are now. I'm very happy with the grain match between the laminated veneers and the solid sapele stock.

All four parts were glued on in one go.

The transitions at the laps were faired and sanded.

Except for bunging and varnishing, the coamings are done!

I still need to bung all the fastener holes, and re-seal the sanded bits and trimmed off bungs before varnishing. I may go ahead and paint the deck next. We're getting closer!

Friday, July 27, 2012

First, a little interesting news- Back in May, I submitted a photo to Jamestown Distributors Facebook page for a contest they were running, and won $100 worth of merchandise! I had a funny feeling when I sent it in that it might win. I don't know how long this link will be active, but for now it is. Also, there is talk of including the photo and maybe a little editorial background info in their 2013 catalog. We'll have to wait and see. Meanwhile...

As I mentioned previously, I have to wait to paint the sheer strake until the last fasteners are in, and this means fitting support blocks for the big stand-up rowlocks. These are monumental things that have a big lever arm, so what holds them up has to be pretty strong.

These rowlocks are 15" long, with a 5 1/4" shaft!

The stand-up locks share the same oarlock pads as the forward most rowlocks. They should be installed fairly close to the center of the boat which will allow pushing the boat either bow or stern first. Mine worked out to be about 6" forward of amidship. There is comfortable standing space aft of the dagger trunk to push the boat with the oars facing forward, but probably not so comfortable facing aft, because of the forward thwart. We'll see how this all works out.

To start with, I plotted the oarlocks' positions on the deck. I put the center of each lock about 12" aft of the aft edge of the thwart. On this boat, there are two sitting positions, pulling either two or four oars, and a single stand-up position as I mentioned previously. Because of the length of the stand-up shafts, and the flare of the sheer strake, some careful layout was needed to make sure there was room for the shaft to pass through it's support block, and not hit the inside of the plank. I laid this out in section, full size, to find the location of the pads on deck.

This is a murky photo of the full size layout, on a scrap of mdf.

The pads elevate the locks a little above the deck, and provide more bearing for the lock casting than just the decks would. The pads must be curved to fit the deck in plan, and tweaked a little where they bear on the deck to address the very slight twist and concavity as the deck follows the sheer curve. I first made patterns for both sets of pads, and laid out the lock centers on them.

Oarlocks, patterns for the pads, and the pads themselves.

The pads need a little profile shape so as not to look clunky, and a long ogee works well for that. I happened to have an appropriate pattern for the edge shape from a previous boat, and dug that out. I made the pads from sapele, to match the coamings and rub rails, sawing out the plan curve first, then the profile shape. I cleaned up the ogee cuts on the spindle sander. The aft pads have just one hole for the oarlock casting, but the forward pads have this hole, plus the bore for the stand-up lock. The stand-ups go through wood only. I planned the bores in the pads to be perpendicular to their top surfaces. These were drilled out on the drill press, along with the fastener holes for the pads themselves.

The pads are bored on the drill press.

The full set of oarlocks and pads. the pads are shellac sealed.

Instead of wood screws, I bored for #10 flat head machine screws. I should mention here that I glued on ply doublers under the deck in way of the pads, for extra stiffness. I clamped the pads on the deck, and bored through the deck for the fasteners. The forward pads have an extra set of machine screws through the bronze lock castings, to provide yet more support for the stand-ups. I then put in all the screws and ran the nuts and washers up tight, and bored the shaft holes through the deck, using the pad bores to keep everything lined up.

The forward starboard oarlock pad, prior to boring out the deck.

Next I made the stand-up support blocks that get fastened to the inside of the planking. These are sapele also, but were painted to match the inside of the hull. The bore for these blocks is at an angle, which I found in the full size layout that I did. I tilted the table on the drill press, and bored the blocks before shaping them to somewhat of an oval.

Stand-up rowlock support block.

The support blocks, before lanyard holes were drilled.

It occurred to me (not too late for once) to also bore small holes for rowlock lanyards. These lanyards keep the locks from being lost overboard (I have a good $300 in oarlock hardware on this boat!). Inside the boat, I taped off the locations of the support blocks, and sanded away the paint for a good epoxy bond to the plank.

Paint is sanded away to permit bonding of the support block.

Before gluing them in though, I primed and painted the blocks, and carefully checked the fit of the rowlock shafts through the pads and blocks. I then installed them with screws through the planking. Now I can paint the sheer strake at any time.

The fit is checked...

... and the blocks are painted prior to installation (note lanyard holes).

I'll put several coats of varnish on the pads, and finish-paint the deck before permanently installing them. I don't want to glue these on, but will bed them right on the painted deck with an oil base bedding compound. I had glued Cricket's pads on with epoxy, then had to chop them off with a big chisel when I wasn't satisfied with their placement. Live and learn!

The starboard aft pad, in position.

The oarlock locations are evident in this shot.

A final note, while we are on the subject of oars. I've been thinking about what style oars I might make for this boat, out of what material, and how much time it will take, when out of the blue a nice pair of Shaw and Tenney's of the right length, kind of materialized. Ashok, my shop assistant was up in the Catskills on vacation and stumbled on a perfect pair, in an antique store of all places. The oars are quite old (maybe 30 or 40 years?) and belonged to the proprietor's dad, but they were little used, and have only a patina to show their age. $125! Quite a good deal. These oars have copper tips too, and are leathered and buttoned. The grips seem a trifle short, and I wonder if they were cut at some time to fit in a particular space. Anyway, we'll see how they work and I can always add a little length to the grips later if need be. For now though, that's one less thing to worry about.

Thursday, July 26, 2012

I've actually been moving along on the boat, but I'm woefully behind on the blog posts. I hope to catch up soon, and I am going to make an effort to keep up with it, and also to add some non Matinicus posts. I've been working on a new boatbuilding shop at Sebago, a very nice 800 square foot shop with big sliding doors and benches, etc. but more on that down the road.

For now, let me catch us up quickly with some exterior hull painting that I completed a couple of months ago. Before painting, I covered the plank keel with a single layer of 6 oz glass (for abrasion), and wrapped the interior of the daggerboard cut out as well.

Glassing the keel.

Glass is also folded down into the dagger slot.

The interior of the dagger trunk was covered in glass cloth before I put it together, so the keel cutout application completed the covering. I scuff-sanded the glass, and filled the weave with a thin fairing mix, then faired in the overlaps before painting with Petit primer/underbody. I spent a bit of time filling screw holes and touching up the lower plank scarfs. I had glued up the first few plank scarfs right on the boat, but was not happy with that result, so subsequent planks were scarfed on the bench (or floor) before hanging. This was a much better method, at least for me.

Petit primer/underbody is applied and sanded out.

I then sanded out the primer with 220 tri-m-ite. I was surprised at how many scratches and what-not that it filled. I probably could have used another coat of underbody, but I felt like it was good enough. The proof is in the finish, and that speaks for itself!

Petit "mist grey" easypoxy.

Petit "mist grey" easypoxy.

This is three coats of Petit Easypoxy Mist Grey. The sheer strake will be Hatteras White, which I'll do after fastening the stand-up oar lock support blocks. That is what we'll do next.